API referenceInvoices
Cancel an invoice (Stornorechnung)
POST
An issued invoice cannot be changed. It is cancelled by a cancellation invoice (Stornorechnung) with negative amounts, which this answers with 201. An invoice cancelled already answers 200 with the cancellation invoice that cancelled it. Scope partner:invoices:write.
apiKey partner:invoices:writeheader
AuthorizationBearer <ab_…>An API key from Integrations → Connect AI assistants (MCP) → New access, bound to exactly one company. Each operation names the scope the key must carry.
Scope: partner:invoices:write
invoice_id*Invoice IdAlphaCount-Version?stringThe API version to use. Default: the current one.
OK
application/json- response
amount_paid*Amount Paidcancelled_by*|nullcancels_invoice*|nullcontract_external_ref*|The contract that billed it, if any.
currency*Currencycustomer_external_ref*string|nulldue_date*|nulldunning_level*|Highest dunning level sent (0 = payment reminder).
external_ref*string|nullexternal_source*string|nullid*Idissue_date*|nullnumber*|Invoice number; null while a draft.
overdue*Overduepaid_at*|Paid in full, UTC.
sent_at*|First mail, UTC.
service_period*status*StatusValue in
"draft""issued""sent""partially_paid""paid""cancelled"total_gross*Total Grosstotal_net*Total Nettotal_tax*Total Taxtype*TypeA cancellation invoice (Stornorechnung) is type storno with negative amounts.
Value in
"invoice""storno"curl -X POST 'https://app.alphacount.ai/api/partner/v1/invoices/string/cancel' \ -H 'Authorization: Bearer ab_...'Example Response
{ "amount_paid": "0.00", "cancelled_by": null, "cancels_invoice": { "external_ref": "order-2", "id": "00000000-0000-4000-8000-000000000002", "number": "RE-2026-0001" }, "contract_external_ref": null, "currency": "EUR", "customer_external_ref": "org-17", "due_date": "2026-10-19", "dunning_level": null, "external_ref": null, "external_source": null, "id": "00000000-0000-4000-8000-000000000001", "issue_date": "2026-10-19", "number": "ST-2026-0001", "overdue": false, "paid_at": null, "sent_at": null, "service_period": { "end": "2026-10-31", "start": "2026-10-01" }, "status": "issued", "total_gross": "-119.00", "total_net": "-100.00", "total_tax": "-19.00", "type": "storno"}